1. Technical Field
Embodiments of the present invention generally relate to a process unit and an image forming apparatus, such as a copier, a printer, a plotter, or a multifunction peripheral (MFP) having at least two of copying, printing, facsimile transmission, plotting, and scanning capabilities, that incorporates the process unit.
2. Description of the Related Art
Image forming apparatuses, such as copiers, facsimile machines, and MFPs (or multifunction machines) having such capabilities, typically include a rotatable image bearer, such as a photoconductor drum, to bear a toner image and a developing device provided with a developing roller to supply toner, as developer, to the photoconductor drum. The toner image on the photoconductor drum is transferred onto a recording medium such as a sheet of paper. The developing device further includes a supply roller to supply toner to the developing roller.
The developing roller rotates while contacting the photoconductor drum and the supply roller. Since friction is thus generated on a surface thereof, it is preferred that the developing roller have relatively high degrees of slidability and durability. Preferable image formation can be attained when the developing roller supplies toner uniformly to the photoconductor drum.
Additionally, an edge of a regulation blade and a seal member to inhibit leak of toner contact axial end portions of the developing roller. Since friction is generated between the developing roller and these components, it is preferred that the slidability and durability are higher in the axial end portions of the developing roller.
To attain reliable image formation, slidability and abrasion resistance of the developing roller may be enhanced by, for example, surface treatment, coating, or machining of the entire developing roller or such processing of the axial end portions.